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2020 Kia Sedona EX
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8 Posts
Discussion Starter #1
I've got about 6000 miles on it so far. If I push the accelerator to the floor, it zooms just fine - very smooth acceleration. But if I'm slowly accelerating, or even trying to maintain speed but going uphill, I feel these little 'bumps' in the power of the van. Most of the time they're so subtle they just feel like bumps in the road. But every now and then I'll feel a larger one. It feels like there was a tiny blip with zero power. They come randomly.

Is this something I just have to expect with the 8 speed transmission? Should I take to to the dealer, or am I just being silly? My wife's driven the van almost a much as I have, and only notices these hesitations when I point them out to her.
 

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Sorento 14, Sedona 17 LX+
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44 Posts
If your model has an ECO mode button and you have it turned on, try turning it off and see if that changes anything. I can't stand to have ECO mode on in my 2017 w/ 6 speed, as it causes mildly erratic/goofy shift and acceleration behaviors during light to moderate acceleration.
 

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2020 Kia Sedona EX
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8 Posts
Discussion Starter #3
Yeah, sorry, I should have added that to the initial post. That mode button has three settings (Eco and two others, which I don't remember off the top of my head right now) and no matter which one I use, the little power glitches remain. I'm not able to feel any difference in the glitching as I switch between the three modes.

Also I've tried using cruise control and the power glitches are there as well.
 

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'15 Kia Sedona SX
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157 Posts
My answer may not be responsive to your particular situation, but if hesitation was common we'd surely have heard some grousing here on the forum--unless you are the first '21 owner here. Also, given that the 6-speed has no such widespread problem, I choose to believe that KIA would not take a step backward in that regard. A quick forum and Google search reveals no apparent pattern although, as with any car, there are some isolated reports,

Common reasons for engine/transmission hesitation:
  • Mass Airflow Sensor: The mass airflow sensor measures how much air is entering the engine and relays this information to the vehicle’s computer so that the right amount of fuel can be delivered from the fuel injectors. When a mass airflow sensor begins to fail, it will typically generate an error code or “Check Engine light.” This warning may be accompanied by hesitation while accelerating, or while driving up a hill. A vehicle with a failing mass airflow sensor may also stall soon after starting.
  • Fuel Pump: The fuel pump in most modern vehicles sits inside the fuel tank and pumps fuel up to the engine. If a fuel pump cannot provide the correct pressure, fuel may have difficulty making it to the engine. A vehicle that hesitates while accelerating or while driving up a hill may have a weak fuel pump.
  • Throttle position sensor: A throttle position sensor tells the vehicle’s computer how far the throttle is open and how hard the accelerator is being pressed. The computer is then able to adjust the fuel/air mixture going to the engine so that it stays at an appropriate level. If the throttle position sensor is not working properly, it may be sending incorrect information to the vehicle’s computer. The computer may then not provide the engine with the correct amount of air while accelerating, causing a hesitation sensation.
  • Dirty/failing fuel injectors: Fuel injectors spray fuel in a fine mist into the cylinder where it is mixed with air and ignited by a spark plug. Fuel injectors may become dirty over time and not be able to provide as much fuel to the cylinder as is needed. Dirty fuel injectors may cause the engine to run lean which will in turn, cause hesitation when accelerating.
 

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2020 Kia Sedona EX
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8 Posts
Discussion Starter #5
Thanks darisgin - I think you're right. If it's just me, then it's something wrong with just my van and I need to take it in. Sigh. So it goes-
 

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2015 Sedona SX-L
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38 Posts
What you describe sounds like torque converter shudder. You will usually experience this in one of the higher gears at lower RPMs and mid to high engine load (accelerating). It happens when the torque converter lockup clutch is engaged, there will be a shudder that sometimes feels like a hesitation or misfire.. Some people describe the feeling like running over a cattle guard or bumps in the road.

Here's an article that describes what the shudder is and what causes it. It's actually fairly common in modern vehicles because newer transmissions are quite aggressive in engaging the lockup clutch in order to achieve better fuel economy. In older vehicles TCC lockup only occurred in the overdrive gear once you were well up to cruising speed. Nowadays the clutch is engaged as early as 3rd or 4th gear while you are still actively accelerating, and this is when the problem is most noticeable. You will be able to tell when the lockup occurs because the RPMs will drop slightly (usually 300rpm or so) as if an upshift had just occurred-- right after that "fake upshift" (assuming you are still accelerating) is when you'll notice the shudder the most. See if that's the case with your car. Often times changing the transmission fluid will fix it, sometimes it's just inherent in the transmission design, and other times there's a mechanical issue (torque converter or lockup clutch) behind it.

Not saying this is your problem 100%, but it's not terribly uncommon on newer cars where fuel economy is becoming a bigger and bigger priority.

What is Torque Converter Shudder? - Roadrunner Converters
 

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2020 Kia Sedona EX
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8 Posts
Discussion Starter #7
Thanks 00sportage20 - that is a very education article and I appreciate you sending it to me.

If I just felt one such glitch or bump, I would strongly suspect torque converter shudder. But as I'm driving along (without the van switching gears - at least that I can tell), say up a gentle incline (not changing speed) I'll get many of these glitches or bumps - say an average of 5 every 10 or 20 seconds. Based on your description and the article, I'm thinking that torque converter shudder is not the problem here. But I could be complete wrong.

*Brian
 

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2015 Sedona SX-L
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38 Posts
Actually torque converter shudder doesn't usually cause a single hiccup (or "bump") but rather the "bumps" tend to repeat. It's the clutch grabbing and slipping, grabbing and slipping, the process usually repeats which is why it's called shudder. It usually goes away once you reach sufficient speed, or you lighten the load on the engine (reach top of hill, get to cruising speed, raise engine RPM.)

If the condition is repeatable, you might try going into "sport mode" and downshifting manually to the next lower gear next time you expect this to occur. If it still occurs in the lower gear (where the engine RPM is raised and engine not as loaded) it's almost certainly not torque converter shudder.

A misfire would greet you with a blinking CEL, and any bad or suspect engine management component (sensors and such) would probably have triggered a fault code / CEL by now. Obviously there are rare exceptions, but this seems to me more transmission related than anything.
 

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2020 Kia Sedona EX
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8 Posts
Discussion Starter #9
Ahhh! Yes! That makes a ton of sense now. And I will absolutely try the downshift - excellent suggestion! Thank you so much-
 

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2015 Sedona SX-L
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38 Posts
I only mention it because we have a Chrysler product with the 62TE transmission that's well known for TC shudder. My wife rarely notices it, but when she does she describes it as "tugging"-- basically a momentary loss of power that repeats. Feels like hitting bumps in the road. Ours does it most when we hit 5th gear (usually at about 40-45mph) while accelerating gently, or if we're trying to maintain speed going up a slight incline. But it will also do it at higher speeds in 6th with the same conditions (accelerating gently / going up hill). If I give it gas and prompt a downshift, it disappears. Your description sounds like what we experience to a T.

That said, torque converter shudder is not just a Chrysler problem, it affects transmissions by all manufacturers. It's a big reason transmission fluids keep changing, because manufacturers are using different formulas/friction modifiers to keep it to a minimum. It's a common complaint on a lot of newer cars. The root cause in my opinion is the torque converter clutch locking up too early, which manufacturers are doing to increase fuel economy.

Might not be the problem, just be aware of it and perhaps mention it when you talk with your dealer, especially if downshifting causes the problem to go away.
 

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2020 Kia Sedona EX
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8 Posts
Discussion Starter #11
So, if it is TC shudder, it sounds like there's nothing that can be done about it - it's a feature not a bug. I mean, it's really not that big of a deal - if I know that it's just a tradeoff they made for fuel efficiency, then I'm OK with just ignoring it. I wonder what my dealer will say though. I'll schedule an appointment with them, and let you all know what they say. Thanks again for all of the help!
 

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2015 Sedona SX-L
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38 Posts
Some transmissions are more prone to it than others. I don't know enough about the new 8 speed in the Sedona to know if this is a common complaint. If it is and the shudder is not excessive, the dealer is likely to suggest that it's normal. If TC shudder is something they rarely encounter and transmission is not known for (or they consider it excessive), they might start looking for a mechanical problem that might be causing it.

On transmissions where the shudder is sort of "engineered in" (common), it usually doesn't cause any problems in the long run, and most mechanics / dealers deal with it by just saying it's normal or adding a friction modifier additive to minimize it-- usually the additive approach does work.

Good luck and keep us posted, I'm curious to know what it is.
 

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2020 EX Premium Silver
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2 Posts
I've got about 6000 miles on it so far. If I push the accelerator to the floor, it zooms just fine - very smooth acceleration. But if I'm slowly accelerating, or even trying to maintain speed but going uphill, I feel these little 'bumps' in the power of the van. Most of the time they're so subtle they just feel like bumps in the road. But every now and then I'll feel a larger one. It feels like there was a tiny blip with zero power. They come randomly.

Is this something I just have to expect with the 8 speed transmission? Should I take to to the dealer, or am I just being silly? My wife's driven the van almost a much as I have, and only notices these hesitations when I point them out to her.
Embededman my 2020 Sedona EX Premium does the same thing. We just replaced a 2015 SX and it drives totally different than the old van. Almost from day one when I drive the 2020 I feel like there is no power off the line and when I press accelerator it doesn’t respond at all. It gives almost a delayed reaction like it is “building up boost” and then starts to accelerate and rpms go up. We only have 2300 miles on the van and had it about 2 months. My wife agrees with me that there seems to be a “delay” in acceleration.
I have noticed another issue about 4 or 5 times now when accelerating from about 15-20mph up to about 45/50mph the van seem to get stuck in a gear and won’t shift to the next gear. The RPMs stay between 3,000-4,000 while I can fluctuate speed between 40-60mph. It 100% doesnt shift to the next gear and drop RPMs like it is supposed to. It literally just happened tonight while I was driving. That is why I just joined as I got online and started googling the problem. I took my phone out and videoed it so that I can show the dealership. Between that and the acceleration thing I am calling service tomorrow to take this van in. I have only driven the van about 10 times and it has happened 3 times at least that I noticed. That is more than a fluke shift.

Have you noticed this shifting issue while driving? It is very noticeable because the rpms stick up there and you typically don’t drive a car at high speed with those rpms. My wife even mentioned it the first time I noticed it, as we were driving getting on an interstate she said is something wrong with the van? For her to notice that is saying something. I had to baby it until the next exit as it was try to run at 4500 rpms as I approached 60mph. If I shift the van out of Drive and then back it seems to correct it.

I would be curious to know if you ever called Kia and took it in? I will definitely update once i do. If I can get a video uploaded I will upload the non shifting issue I took tonight. All of these issues are happening in Normal mode, not ECO or other one.

Camden
 

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2020 Kia Sedona EX
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8 Posts
Discussion Starter #15
Embededman my 2020 Sedona EX Premium does the same thing. We just replaced a 2015 SX and it drives totally different than the old van. Almost from day one when I drive the 2020 I feel like there is no power off the line and when I press accelerator it doesn’t respond at all. It gives almost a delayed reaction like it is “building up boost” and then starts to accelerate and rpms go up. We only have 2300 miles on the van and had it about 2 months. My wife agrees with me that there seems to be a “delay” in acceleration.
I have noticed another issue about 4 or 5 times now when accelerating from about 15-20mph up to about 45/50mph the van seem to get stuck in a gear and won’t shift to the next gear. The RPMs stay between 3,000-4,000 while I can fluctuate speed between 40-60mph. It 100% doesnt shift to the next gear and drop RPMs like it is supposed to. It literally just happened tonight while I was driving. That is why I just joined as I got online and started googling the problem. I took my phone out and videoed it so that I can show the dealership. Between that and the acceleration thing I am calling service tomorrow to take this van in. I have only driven the van about 10 times and it has happened 3 times at least that I noticed. That is more than a fluke shift.

Have you noticed this shifting issue while driving? It is very noticeable because the rpms stick up there and you typically don’t drive a car at high speed with those rpms. My wife even mentioned it the first time I noticed it, as we were driving getting on an interstate she said is something wrong with the van? For her to notice that is saying something. I had to baby it until the next exit as it was try to run at 4500 rpms as I approached 60mph. If I shift the van out of Drive and then back it seems to correct it.

I would be curious to know if you ever called Kia and took it in? I will definitely update once i do. If I can get a video uploaded I will upload the non shifting issue I took tonight. All of these issues are happening in Normal mode, not ECO or other one.

Camden
Camden,

I haven't had time yet to take it into the dealer (based on the other folks of this forum and their experience, I'm almost 100% confident the dealer will say that its working normally but I'll likely have to leave my van with them for a while for that determination to be made) so I don't have any official answer yet.

However, I've never had quite the issue you're having - my Sedona has never failed to shift up - I've never seen the RPMs race like you are seeing. In fact, I think mine may be the opposite problem - it shifts too early (to try and save fuel) and so you get this 'lugging' or choppy acceleration that I feel. Maybe.

I have been able to completely make the problem go away if I shift completely manually. If I'm making all of the decisions about when to shift, I can't get it to have the issue. So that tells me it's not a problem with my gas, or my injectors, or anything like that, but rather a transmission issue.

I'm still investigating and will report back anything I find out.
*Brian
 

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2020 EX Premium Silver
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2 Posts
Camden,

I haven't had time yet to take it into the dealer (based on the other folks of this forum and their experience, I'm almost 100% confident the dealer will say that its working normally but I'll likely have to leave my van with them for a while for that determination to be made) so I don't have any official answer yet.

However, I've never had quite the issue you're having - my Sedona has never failed to shift up - I've never seen the RPMs race like you are seeing. In fact, I think mine may be the opposite problem - it shifts too early (to try and save fuel) and so you get this 'lugging' or choppy acceleration that I feel. Maybe.

I have been able to completely make the problem go away if I shift completely manually. If I'm making all of the decisions about when to shift, I can't get it to have the issue. So that tells me it's not a problem with my gas, or my injectors, or anything like that, but rather a transmission issue.

I'm still investigating and will report back anything I find out.
*Brian
Brian,

I understand the exact issue your are describing though. I have your same issue as well, with the “lugging” or groggy acceleration. It is strange that I would also have an almost completely opposite issue with my non up shifting.
I will post back with findings.
Camden
 

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'15 Kia Sedona SX
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157 Posts
I'm almost 100% confident the dealer will say that it's working normally...
"Hey, I think there's something wrong with my--"
"It's working normally."
"But I haven't even--"
"It's working normally."
"How do you know that if--"
"It's working normally."
"Could you at least--"
"It's working normally."
 

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2020 Kia Sedona EX
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8 Posts
Discussion Starter #18
Exactly. Grrr. It sure doesn't "feel" normal to me. But - you know - does it matter how it feels if there's no easy way to fix it? :-(
 

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my 2020 ex does the exact same thing. only has 4,000 miles on it. lag in the acceleration, and the minor jerks/bumps when accelerating slowly up until about 45 mph.
 

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99 Kia Elan 1.8L
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11,307 Posts
my 2020 ex does the exact same thing. only has 4,000 miles on it. lag in the acceleration, and the minor jerks/bumps when accelerating slowly up until about 45 mph.
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